Vulnerability-Lookup

GHSA-76V9-JPJ5-V4RQ

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33

Details

In the Linux kernel, the following vulnerability has been resolved:

tipc: fix UAF in tipc_l2_send_msg()

Syzbot reported a slab-use-after-free in ipvlan_hard_header() when called from tipc_l2_send_msg().

The root cause is that tipc_disable_l2_media() calls synchronize_net() while b->media_ptr is still valid. This allows concurrent RCU readers to obtain the device pointer after synchronize_net() has finished. The pointer is cleared later in bearer_disable(), but without any subsequent synchronization, allowing the device to be freed while still in use by readers.

Fix this by clearing b->media_ptr in tipc_disable_l2_media() before calling synchronize_net().

This is safe to do now because the call order in bearer_disable() was reversed in 0d051bf93c06 ("tipc: make bearer packet filtering generic") to call tipc_node_delete_links() (which needs the pointer) before disable_media().

https: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u

Severity

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-74255"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:24Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix UAF in tipc_l2_send_msg()\n\nSyzbot reported a slab-use-after-free in ipvlan_hard_header() when\ncalled from tipc_l2_send_msg().\n\nThe root cause is that tipc_disable_l2_media() calls synchronize_net()\nwhile b-\u003emedia_ptr is still valid. This allows concurrent RCU readers\nto obtain the device pointer after synchronize_net() has finished.\nThe pointer is cleared later in bearer_disable(), but without any\nsubsequent synchronization, allowing the device to be freed while\nstill in use by readers.\n\nFix this by clearing b-\u003emedia_ptr in tipc_disable_l2_media() before\ncalling synchronize_net().\n\nThis is safe to do now because the call order in bearer_disable()\nwas reversed in 0d051bf93c06 (\"tipc: make bearer packet filtering generic\")\nto call tipc_node_delete_links() (which needs the pointer) before\ndisable_media().\n\nhttps: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u",
  "id": "GHSA-76v9-jpj5-v4rq",
  "modified": "2026-08-17T06:33:34Z",
  "published": "2026-08-15T06:32:27Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74255"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0d8a12d7143126afdf9fbe2e3d438650dd6603ed"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/35e0297a93c3c34a3924eeef816c03504e3ab5c5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/50ff092633b06382e5091dd5b093ce943d4ac2f9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/609ced2301be1df7e7ed2ef47d1d916674e6ba3b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/71aafa16d79b107b33837f60b6cbc7d0cb8c5708"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/aef12b5ce793dea6b3a97a58fd0f946000ae8945"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f4002f1c669cc02e3763f479fc25ff1dfa9e2420"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-74255 (GCVE-0-2026-74255)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:57 – Updated: 2026-08-17 05:45

Title

tipc: fix UAF in tipc_l2_send_msg()

Summary

In the Linux kernel, the following vulnerability has been resolved: tipc: fix UAF in tipc_l2_send_msg() Syzbot reported a slab-use-after-free in ipvlan_hard_header() when called from tipc_l2_send_msg(). The root cause is that tipc_disable_l2_media() calls synchronize_net() while b->media_ptr is still valid. This allows concurrent RCU readers to obtain the device pointer after synchronize_net() has finished. The pointer is cleared later in bearer_disable(), but without any subsequent synchronization, allowing the device to be freed while still in use by readers. Fix this by clearing b->media_ptr in tipc_disable_l2_media() before calling synchronize_net(). This is safe to do now because the call order in bearer_disable() was reversed in 0d051bf93c06 ("tipc: make bearer packet filtering generic") to call tipc_node_delete_links() (which needs the pointer) before disable_media(). https: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

8 references

URL	Tags
https://git.kernel.org/stable/c/609ced2301be1df7e…
https://git.kernel.org/stable/c/71aafa16d79b107b3…
https://git.kernel.org/stable/c/f4002f1c669cc02e3…
https://git.kernel.org/stable/c/50ff092633b06382e…
https://git.kernel.org/stable/c/aef12b5ce793dea6b…
https://git.kernel.org/stable/c/0d8a12d7143126afd…
https://git.kernel.org/stable/c/35e0297a93c3c34a3…
https://git.kernel.org/stable/c/f4c3d89fc986b0da1…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 282b3a056225b35024246f63feb91d769d714dad , < 609ced2301be1df7e7ed2ef47d1d916674e6ba3b (git) Affected: 282b3a056225b35024246f63feb91d769d714dad , < 71aafa16d79b107b33837f60b6cbc7d0cb8c5708 (git) Affected: 282b3a056225b35024246f63feb91d769d714dad , < f4002f1c669cc02e3763f479fc25ff1dfa9e2420 (git) Affected: 282b3a056225b35024246f63feb91d769d714dad , < 50ff092633b06382e5091dd5b093ce943d4ac2f9 (git) Affected: 282b3a056225b35024246f63feb91d769d714dad , < aef12b5ce793dea6b3a97a58fd0f946000ae8945 (git) Affected: 282b3a056225b35024246f63feb91d769d714dad , < 0d8a12d7143126afdf9fbe2e3d438650dd6603ed (git) Affected: 282b3a056225b35024246f63feb91d769d714dad , < 35e0297a93c3c34a3924eeef816c03504e3ab5c5 (git) Affected: 282b3a056225b35024246f63feb91d769d714dad , < f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6 (git)
Linux	Linux	Affected: 4.4 Unaffected: 0 , < 4.4 (semver) Unaffected: 5.10.261 , ≤ 5.10.* (semver) Unaffected: 5.15.212 , ≤ 5.15.* (semver) Unaffected: 6.1.178 , ≤ 6.1.* (semver) Unaffected: 6.6.145 , ≤ 6.6.* (semver) Unaffected: 6.12.97 , ≤ 6.12.* (semver) Unaffected: 6.18.40 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
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        {
          "defaultStatus": "unaffected",
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          "programFiles": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix UAF in tipc_l2_send_msg()\n\nSyzbot reported a slab-use-after-free in ipvlan_hard_header() when\ncalled from tipc_l2_send_msg().\n\nThe root cause is that tipc_disable_l2_media() calls synchronize_net()\nwhile b-\u003emedia_ptr is still valid. This allows concurrent RCU readers\nto obtain the device pointer after synchronize_net() has finished.\nThe pointer is cleared later in bearer_disable(), but without any\nsubsequent synchronization, allowing the device to be freed while\nstill in use by readers.\n\nFix this by clearing b-\u003emedia_ptr in tipc_disable_l2_media() before\ncalling synchronize_net().\n\nThis is safe to do now because the call order in bearer_disable()\nwas reversed in 0d051bf93c06 (\"tipc: make bearer packet filtering generic\")\nto call tipc_node_delete_links() (which needs the pointer) before\ndisable_media().\n\nhttps: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u"
        }
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              "value": "AV:N - tipc_l2_send_msg is reached from tipc_bearer_xmit during L2 TIPC protocol handling; remote ETH_P_TIPC frames on cluster/datacenter L2 networks drive outbound transmission that races with bearer teardown in tipc_disable_l2_media.\nAC:L - The UAF window is a race where attackers control both sides by flooding TIPC Ethernet traffic while bearer disable runs and by concurrently triggering bearer teardown; syzbot reliably reproduced this without attacker-uncontrollable timing.\nPR:N - An unauthenticated remote attacker only needs to send TIPC L2 frames on a segment with an active bearer; bearer_disable teardown during cluster failover, netdev unregister, or node shutdown creates the required concurrent disable without attacker-local privileges.\nUI:N - No victim user action is required; exploitation is triggered by remote protocol traffic concurrent with automated or administrative bearer/interface teardown events.\nS:U - Impact is kernel slab memory corruption and potential privilege escalation within the same kernel security boundary, not a cross-VM or cross-namespace escape.\nC:H - Slab use-after-free of a net_device structure via ipvlan_hard_header enables reading freed kernel heap memory and can be leveraged for arbitrary kernel memory disclosure.\nI:H - UAF on net_device during dev_hard_header allows heap grooming and control of freed object contents, enabling arbitrary kernel writes and potential code execution.\nA:H - The UAF causes kernel oops/panic (as reported by syzbot in ipvlan_hard_header) and can be triggered repeatedly to deny service on cluster nodes."
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        "dateUpdated": "2026-08-17T05:45:03.215Z",
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          "url": "https://git.kernel.org/stable/c/f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74255",
    "datePublished": "2026-08-15T05:57:34.293Z",
    "dateReserved": "2026-08-15T05:44:03.876Z",
    "dateUpdated": "2026-08-17T05:45:03.215Z",
    "state": "PUBLISHED"
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.